Quest M3 Mods - Page 4

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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TomC (original poster)
Team HB

#31: Post by TomC (original poster) »

Today I installed my alternate, modified drum into the Quest M3, having a friend cut about a half inch off the rear and weld on a perforated plate. I'm going to leave the original drum completely stock to switch back to if I choose. It's too early to tell if the outcomes are beneficial, but I do like what I'm seeing, for what it's worth. The roaster is as easy to predict and control.

I did 3 batches, and only the last batch was with a good coffee that I was concerned about getting right, the first two were just to see how it behaves. What I'm noticing early on is that the chaff color matches the roasts I get on my 1 kilo roaster. I'm not sticking a flag in the concept and saying it's true, but it leads me to believe that for any given profile, I'm now roasting more convectively and less conductively. Most of the roasts on the Quest over the years have all had darker chaff than the same sort of approach done on the gas roaster (matching grossly 1C times and bean appearance only).

I roasted the Kenyan Gachatha AA ( the original Unicorn) and had the control I wanted and shaped the profile the way needed. I'll see how it brews up over the next few days.



Here's a crappy Instagram picture showing the drum. The perforations are 3/16".






Checking fitment, the drum was removed and a Dremel cleaned up a few rough spots on the front before reassembly.






I'll be continuing to play with it. I didn't put the insulation back on, this was with it entirely removed. I didn't want to put things all back on only to have to take it off again to troubleshoot or fix something. I'll be changing how the outer body is wrapped too, aiming to actually trap a body of air under the roaster so that the air it draws in during the ramp is pre-heated.



No claims at all to superiority of any of this, just playing for now.

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OldmatefromOZ

#32: Post by OldmatefromOZ »

Looks good. I am pretty sure I want to go down this path.

Did you cut more from the length of the drum than the suggested shortening to 6 inch by Mr Bill to be sure it was not a tight fit? Replacement drum for Quest M3 - future modifications

My drum is 6 1/4 inch long and rubs on the back plate pretty much all the way around ( there is a nice clean circle )

Are you still using the stock air inlet hole? I like the idea of blocking that up and cutting some slots under the elements.

Cheers

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TomC (original poster)
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#33: Post by TomC (original poster) »

There's no way it could be a tight fit. The notch on the shaft that mates to the output shaft of the motor is what determines how it sits in the frame of the roaster, not the length of the drum itself.

I know the Quest got a revision with a setup that is more ideal for right handed users, along with that came a thinner drum (my replacement drum is thinner as well) but I'm not sure if the rear of the roaster has changed much. True metal to metal contact would likely fry the motor, or completely seize after the unit came up to temp. The "clean circle" you describe is the channel purposely cut into the posterior wall on mine. The drum originally sat right up close to this area, but never touched it.

I'm going to fiddle around with the way the insulation is wrapped around the outside, before I do anything that is relatively permanent to the outer shell. As it is now, it does what I want it to, so I'm not sure if it will truly need holes cut into the shell right under the elements. But, I can easily imagine that sort of thing helping.

OldmatefromOZ

#34: Post by OldmatefromOZ » replying to TomC »

Thanks.

Just for reference I have 2014 build, also referred to Mk2 I think, with the thinner drum etc.
It does not have the channel you describe in the back plate, totally smooth.

After 6 or so roasts the drum very very lightly rubs on the back plate. I think it is mostly a very tight clearance with perhaps just 1 or 2 spots that expand and touch the back plate - going around making the circle.

Yes, good point about the notches on the shaft that connect to the motor, I was totally focused on drum length / clearance. So your longer cut will result in a bit more space for the air to travel path of least resistance, which sounds good.

I think I might get the metal fabricator to make the drum 6 inches in length total including the new perforated plate.

Anyone have any ideas how wide to make the slots in the outer casing? I am thinking around 3mm

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TomC (original poster)
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#35: Post by TomC (original poster) »

I imagine some trial and error would be all it takes. Although it might not look pretty, Im sure holes could be patched if you didn't like them. I'll experiment more ( I honestly thought I'd have to have the hole/holes relocated as well, but it doesn't seem to be the case early on). It's only another guess, but I imagine the air within the space between the outer shell and drum is quite active. With heat rising and the drum spinning, I can picture in my mind the air circulating pretty well in that cavity. It's clearly not just sucking in cold air from the rear of the roaster or the total roast times would be dreadfully long.

OldmatefromOZ

#36: Post by OldmatefromOZ »

Hmm I might just give it a crack with the existing hole then.

If I was to cut slots, I am thinking it might be a good idea to go close or just slightly more to matching surface area of the hole?

The hole is approx 25mm diameter which means it is approx 490 mm2.

So if I made the slots L40mm W2mm = 80mm2 X 8 ( 4 under each element like Mr Bill ) = 640mm2.

Does one big hole behave the same as 8 small slots in regards to air flow volume / dynamics if the opening surface area is the same :?

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AssafL

#37: Post by AssafL »

Like the idea. Few questions:

1. Might one achieve the same results by drilling small holes in the drum itself 1/2 inch or so from the end of the drum? that will allow air to flow into the drum.
2. That still leaves the issue of the heaters position vis-à-vis the air inlet hole in the back. How do you heat the air that comes in? I was thinking of drilling holes near the heater (in the sleeve) and sealing the back hole.

-al
Scraping away (slowly) at the tyranny of biases and dogma.

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TomC (original poster)
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#38: Post by TomC (original poster) »

Im slightly less inclined to fiddle with the itchy insulation wrap, but I might and do a bit of an A/B comparison, but right now, the Kenya Gachatha Unicorn is the best roast of it to date, so maybe I don't need to bother. I think I've profiled it about 9 times to date. It has a very narrow sweet spot. But this Chemex batch was deeply lush, honeyed currants, very intense.

OldmatefromOZ

#39: Post by OldmatefromOZ »

After much searching I have not been able to find any off cuts of appropriate 304 perforated sheet.

Anything new I would need to buy a ridiculous amount that would cost hundreds of $. I found a metal worker just up the road who came around and had a look at what I wanted to do. He said he would keep an eye out for some scraps. But went on to say he would give me a small square and I could drill my own holes and leave a 5mm gap around the edge to make cleaner more secure weld to the drum.

He is going to shorten the drum by 1cm which will slightly cut into the end of the vanes and he said he will make it so that the angle is exactly the same as it is now.

Also going to cut the slots in outer shell for me. I will be blocking up the existing air hole with a silicone stopper / bung .
Total costing around $60, which I am quite happy with.

Holes are being drilled by hand drill :cry: with a 4.5mm cobalt bit. I am going to be TRYING for 6 - 7mm stagger. Lining up the centre punch right in between 6 - 7mm. Certainly wont be anywhere near perfect, but should do the job.

I did not start of so good having never drilled SS before, getting better as I go. Very slow and steady firm pressure is hard going on arthritis. Might get them all done over the weekend? :roll:


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TomC (original poster)
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#40: Post by TomC (original poster) »

AssafL wrote:Like the idea. Few questions:

1. Might one achieve the same results by drilling small holes in the drum itself 1/2 inch or so from the end of the drum? that will allow air to flow into the drum.
2. That still leaves the issue of the heaters position vis-à-vis the air inlet hole in the back. How do you heat the air that comes in? I was thinking of drilling holes near the heater (in the sleeve) and sealing the back hole.

-al

Sorry, I didn't see this till now. I had considered doing something like that, but I couldn't picture in my head how I'd be able to drill a sufficient quantity without grossly distorting the roundness of the drum. Plus it would take a significant amount of holes drilled and any coffee that is sitting in that section of the drum will get different levels of conductive heat transfer than the coffee towards the front. Plus there's way more places for chaff to get stuck or bits of beans to get stuck and being that close to the heat source just sounds like a really bad idea all around. I wouldn't recommend going that route.

It was far easier for my buddy to just mount it on his lathe, trim off the back and tack weld the screen on. He said it was an hour of work, only because he had to undo the mistake he made ( welding the wall onto the front by mistake) before redoing the work on the rear. So the front isn't pretty, but darn it works nice.

One observation that I'm noting so far that I like is that I can just leave the airflow maxed out at 1C and just tapper off the heat. I get cleaner coffee (less chaff) and the cup results are screaming at me that I should have done this long ago.